container.hh

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// SPDX-FileCopyrightText: Copyright © DUNE Project contributors, see file LICENSE.md in module root
// SPDX-License-Identifier: LicenseRef-GPL-2.0-only-with-DUNE-exception
// -*- tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*-
// vi: set et ts=4 sw=2 sts=2:
#ifndef DUNE_COMMON_CONCEPTS_CONTAINER_HH
#define DUNE_COMMON_CONCEPTS_CONTAINER_HH

// check whether c++20 concept can be used
#if __has_include(<version>) && __has_include(<concepts>)
  #include <version>
  #if  __cpp_concepts >= 201907L && __cpp_lib_concepts >= 202002L
    #ifndef DUNE_ENABLE_CONCEPTS
    #define DUNE_ENABLE_CONCEPTS 1
    #endif
  #endif
#endif

#if DUNE_ENABLE_CONCEPTS

#include <concepts>
#include <iterator>

namespace Dune::Concept {

template<class T>
concept Container =
  std::regular<T> &&
  std::swappable<T> &&
requires(T a, const T ca)
{
  typename T::value_type;
  requires std::unsigned_integral<typename T::size_type>;
  requires std::forward_iterator<typename T::iterator>;
  requires std::forward_iterator<typename T::const_iterator>;
  { a.begin()    } -> std::same_as<typename T::iterator>;
  { a.end()      } -> std::same_as<typename T::iterator>;
  { ca.begin()   } -> std::same_as<typename T::const_iterator>;
  { ca.end()     } -> std::same_as<typename T::const_iterator>;
  { a.cbegin()   } -> std::same_as<typename T::const_iterator>;
  { a.cend()     } -> std::same_as<typename T::const_iterator>;
  { a.size()     } -> std::same_as<typename T::size_type>;
  { a.max_size() } -> std::same_as<typename T::size_type>;
  { a.empty()    } -> std::convertible_to<bool>;
};

template<class T>
concept RandomAccessContainer =
  Container<T> &&
requires(T a, const T ca, typename T::size_type i)
{
  requires std::same_as<typename T::reference, typename T::value_type&>;
  requires std::same_as<typename T::const_reference, const typename T::value_type&>;
  requires std::random_access_iterator<typename T::iterator>;
  requires std::random_access_iterator<typename T::const_iterator>;
  { a[i]  } -> std::same_as<typename T::reference>;
  { ca[i] } -> std::same_as<typename T::const_reference>;
};

} // end namespace Dune::Concept

#endif // DUNE_ENABLE_CONCEPTS

#endif // DUNE_COMMON_CONCEPTS_CONTAINER_HH